Reduce size and cost of AccessTokenConsumer

[d1ll0n]

Replaces all of the code for verifying access tokens in the consumer contract with a single consumeAccessToken library function which extracts the access token and signature from the call context. Also changes the solc version to 0.8.24 and enables viaIR.

The main improvement here is in getting rid of solc's handling of encoding, which is highly inefficient. It also avoids allocating any memory during this process, which will have significant savings for any inheriting contracts that use a lot of memory, as the current version allocates 742 bytes of memory permanently, making contracts automatically be past the point of linear memory costs.

With these changes, here is the gas and code size diff for the MockConsumer contract - it reduces the size by ~60% and the gas by ~3-4%:

Here is the diff if the solc version is kept at 0.8.13 and viaIR is kept disabled - most of the gas savings remain intact but codesize is only reduced ~30%: